TxOS (Transmit Opportunity) ?

[atul.2.jain]

How does a client gets an opportunity to transmit while it is in race with many other clients to transmit its data? The STA announces its NAV and gets opportunity when its back-off timer expires and it finds that the transmission channel is free but how is it ensured that other clients connected to the same AP would also get an opportunity to transmit?

[Viten Patel]

Hi Atul,

this is a complex mechanism but i will try and simply the answer. if there are multiple devices trying to contend for the air time to transmit data, the random back off timers are different. lets say somehow two clients land up getting access to the channel at the same time there will be a collision and they ll back off again.

there are 2 detection mechanism, one using NAV (layer 1) and other using the duration time in the mac header (layer 2).

let me know if there are follow up questions.